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' A. GRE EN METHOD OF AND MEANS FOR GENERATING GEAR TEETH May 11 1926.

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A. GREEN Msmon 0 AND MEANS FOR GENERATING GEM! TEETH Filed July 12. 1923'7 Sheets-Sheet 2 2 7 2667% 07' Q2202? iffw Mw 9P7? 7 May 11 1926.

A. GREEN METHOD OF AND MEANS FOR GENERATING GEAR TEETH Filed July 12,19255 7 Sheets-Sheet 5 May 11 1926. 1,583,790

A. GREEN METHOD OF AND MEANS FOR GENERATING GEAR TEETH Filed July 12,1925 7 Shets-Sheei. 4

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A. GREEN 4 MEZIHOD OF AND MEANS FOR GENERATING GEAR TEETH Filed Ju1y l2.1925 7 Sheets-Sheet 5 EU UL Q May 11 1926. 1,583,790 1 A. GREEN METHODOF AND MEANS FOR GENERATING GEAR TEETH Filed July 12.. 1925 7Sheets-Sheet s May 11 ,1926. 1,583,790

A. GREEN mz'wuon OF AND msms FOR GENERATING GEAR TEETH Filed July 12.1925 7 Sheets-Sheet 7 Patented May 11, 1926 UNITE- stares ALLAN GREEN,or summon, NEAR nnrennnr', nnennnn, assrenon T DAVID BROWN AND SONS(HUDDERSFIELD) LIMITED, OF

ENGLAND.

LQCKIVGOD, HUIDDEESFIELD, YORK,

METHOD OF AND MEANS FOR" GENERATING GEAR TEETH.

Application filed July 12,

In the cutting or generating of the teeth of toothed gearing (includingthose Wheels which have single helical or double helical teeth) andinthe performing of like op- 6 erations wherein the work is fed to the cutters or the cutters are fed to the work in both a lateral andlongitudinal direction and wherein the cutting tools fill orapproximately fill the cross sectional area of the spaces which they cut(as for example in carrying out the process or method, in whichreciprocating cutters are made use of and in which said cutters aremoved crosswise of the metal blanks, or discs that have to be out whilesaid discs are revolving), I have found that the actions of the cuttersupon said discs when cutting in the ordinary manner or method asheretofore followed, have the effect of forcing against or pres. ing insuch a direction upon the sides of the grooves which they are formingthat such jamming and other resistances are encountered as cause thebearings either of the cutters or of the blanks to spring or yield to anundesirablee-Xtent. My present invention consists in following such amethod of cuttingor generating said toothprofiles and inso using deviceswhich enable me to carry said method into effect, that I avoidexercising any undesirable pressure against the side or lateral surfacesof the teeth which are being generated or of the the space being cutwith greater accuracy as well as being enabledto carry out the cuttingoperations with an'increased feed and therefore with a greater output ofwork than is the case when cutting teeth by the method heretoforefollowed. My method may-be briefly said to consist in performing thefeeding operations by such relative move- I mentsthat the major portionof the cut is effected by the two cuttingedges of each cutter whichrespectively determine the depth and form one side of the cut (theseedges being called the depth cutting) edge and the lea ding cuttingedges, while the other cutting edge called the following edge is onlyrequired to perform minor cuts as when form ing the profilecurve of atooth.

In the carrying out of my invention in connection with machines forgenerating the 1923; Serial N0. 651,060.

teeth of wheels in which the rotating of the blank or the rolling ofsame is in the path of a tangentially moving cutter which cutter hasalso reciprocatory motion transmitted to it, the depth cut is taken bythe depth cutting edge instep by step order, while the generatingcutting actions are effected by a continuously advancing tangential feedand to these two combined movements I now add a third or differentialmove ment which I carry out simultaneously withthe step by step depthfeed.

In orderto explain fullyiny invention I hereinafter dcscribehow I carrysame into oii'ect by the use of various well known types or classes ofmachines which I arrange to operate according to my said invention.These machines and parts are illustrated by the accompanying sheets ofdrawings in which I r Fig. 1 is a side elevation of a machine of knowntype for cutting (with rack cutters) double helical teeth, said machinehaving applied to it my improvedmechanism.

Figs. 2 and 3 are a sectional plan and an elevation showing my improvedparts which I add to the machine shown by Fig. 1.

Fig. 4 is also a side elevation of certain parts of the machine shown byFig. 1 but as scenfrom theopposite side thereof.

Fig. 5 is an elevation of the machine shown by Fig. 1 when viewed in thedirection from left to right of said figure.

Fig. is an elevation showing a modified form of machine to which myinvention is applicable.

Fig. 7 is edge View of a portion of a wheel showing a double helicaltooth.

8 and 9 are diagrams showing the progressive stages of the cuttingactions when the cutter is acting under the old and well known method ofcutting and when no other motion than the cutting motions are beingperformed. 7

Figs. 10 and 11 are similar diagrams to Figs. 8 and 9 and are made toshow the stages or progress and direction of the stages followed undermy new method of producing the teeth desired.

Fig. 12 shows a blank and a rack cutter in relative positions just priorto the commencement of the cutting operations to form the teeth of theshape shown in broken lines on the blank.

Fig. 13 is a similar view to Fig. 12 but shows the blank as advanced onestage and the rack as having taken its first cut on certain parts of theblank.

Li is also a similar view to Fig. 13 but shows by the advancing of thecutter and the blank that certain of the teeth which have passed saidcutter have received the second out while the following teeth show thefirst cut as illustrated by Fig. 13.

Fig. 15 shows the third cut that has been taken in the teeth which havepassed the rack cutter while on the remainder of the teeth the secondout only has been taken.

Fig. 16 shows the blank with the teeth which have passed the cutterfinished while the others require the last out to finish them.

Fig. 17 is a plan showing a rack and cutters for producing same.

In the ordinary process of cutting teeth of the character described eachcutter aof the series of cutters in the rack 2 is caused to advance andcut with its front end Z) and inclined cutting edges and (Z (whichextend from said end 6 to the base 7 of the cutting tool 2) so thatthese cutting edges cut their way and enter centrally as shown by Figs.8 and 9 in order to carry out the cut by the depth cutting edge 6cutting its way inwardly and the two lateral edges 0 and (Z cutting thespaces on each side thereof equally, thus the centre of the cutter (I,always follows the centre of the groove that it produces. Fig. 8 andFig. 9 show the effect such a cutter has upon the blank 3 when saidblank is held against rotation during the cutting operations of thecutter a. The parts in broken and section lines on Fig. 8 indicate whatthe finished groove will be like when produced. under such conditions,while Fig. 9 shows the varied stages that the cutter a advances and cutsin a forward direction and to each side thereof in the proportions shownby broken lines in the blank 3.

According to my method I now arrange the cutter to commence its cuttingoperations (as shown by Fig. 11) below the central line of the spacethat it will eventually cut in the periphery of the blank 3 under theconditions before stated, that is to say, with the blank 3 stationaryand the cutter advancing towards the centre thereof under my improvedarrangement. My improved method consists in causing the cutter toadvance to cut with its depth cutting edge Z) as heretofore but inaddition to advancing the cutter a I also move it relatively with theblank 3 (or laterally in a direction indicated by the arrows w) such aspace as will carry said cutter a forward a distance indicated by thespace between the broken lines A B and C-D on said Figs. 10 and 11,while the blank 3 is stationary, thus the cutting ac tions under myconditions show that the end of the cutter and the edge 0 of said cutterperform (according to Figs. and 11) the entire cut producing the spaceof the shape shown in broken section lines Fig. 10 and in stages asshown by broken lines in Fig. 11.

When generating the proper shape of teeth or teeth having the requiredprofile the variations from said straight sides produced by the cuttingedge 0 and the cutting edge (Z are varied by the additional movements ofthe blank 3 and the cutter 2 when said blank 3 and cutter 2 are beingmoved so that the one rolls over the other in the ordinary methodfollowed in the generating of said type of teeth,

By making use of this additional movement of the cutter 2 relatively tothe rolling or revolving movement of the blank 3 I increase saidmovement of the cutter 2 in addition to its ordinary advancing movementin the direction indicated by the arrows so that I have this additionalrelative movement carried out and the process of cutting of the tooth ofthe wheel secured as is illus trated by Figs. 12 to 16 inclusive. Thatisto say, if the pitch of the teeth being produced is one inch heretoforethe advancing action of the cutter 2 has been one inch of tangentialmotion in the direction indicated by the arrows 10 while the blank 3 hasrotated one inch on the pitch line from one tooth to the centre line ofthe next tooth in the direction indicated by the arrows (c. I now causesaid cutters 2 to advance more than said inch of pitch and the increaseis exactly equal to the inclination of the side cutting edge (Z to astraight line A-B drawn at right angles to the base of the cutters fromthe outward corner of the cutting edge F) and (Z as shown by Figs. 10and 11, thus if the rear edge (Z of the cutting tool a is fourteen andone half degrees at an angle to the line A B which is at right angles tothe base of the cutting tool, then the advancement of the cutter 2during-the time from taking thefirst cut by the outer end of the tool Z)as shown by Fig. 12 until said outer end has reached the depth of thegroove ,that it has to form (as is shown by Fig. 16) is increased by thelength of the base of the triangle (shown by Figs. 10 and 11) formed bythe cutting edge (Z with the line AB and a line from the point it to thepoint 9.

In an inch of depth of tooth the extra advancing of the tool 2 will beapproximately a quarter of an inch, it may be more or it may be lessaccording, as is before stated, to the angularity of the edge (Z of thecutting tool to the base of said tool.

By this arrangement and method of cutting the depth and leading cuttingedges are caused to effect they major portion of the cut and thefollowing cutting edge is caused to effect only a minor portion, so thatall not putting too great a pressure upon the blank 3 and upon thecutting tool 2 a more accurate formation of tooth is secured.

As is hereinbefore stated I may make use of varied forms of mechanismfor obtaining the relatively increased speed of the cutter 2 as comparedwith that of the blank 3 so that I would have it understood that thedevices which I actually employ and which I hereinafter explain are tobe taken as only those which I have proved will efficiently carry out myimproved functions, while I am aware that it may be possible for othermechanism and devices to be produced to attain the said object of myinvention.

The devices shown by Figs. 1 to 5 illustrate the application of myimproved parts to a well known type ofmachine for cutting the class ofWheel to which my invention relates. I

In this type of machine the rack cutters 2, 2 are reciprocated in theirinclined paths in well known manner and by well known mechanism, whilethe blank 3 is mounted to be rotated by the worm wheel 5 so that suchblank 3 (shown in broken lines Fig. 1) by being fixed upon the shaft 60fsaid worm wheel 5 revolves in the direction indicated by the arrow ofsaid figure.

The rotary motions of the wheel 5 are effected by the worm 7 which issplined upon a shaft 8 deriving its motion from change speed gearing atthe end thereof in well known manner in order that the relative speed ofthe shaft 6 with the advancing motion of the bearings or carriage 8 uponwhich the cutters 2 are mounted, are such that the blank 3 carried inits rotary motions will roll over the cutters 2 in well known manner.

During the rotary motions of the blank 3 as is effected by the wheel 5,the tool carriage or bearings 8 upon which the cutting tools 2, 2 aremounted, is caused to rise by the actions of the screw 9 as effected bythe gearing 10, 10 shaft 11 and change speed gearing 12 so that asbefore stated the rising motion of the tool carriage 8 relatively to therotations of the blank 3 is maintained or is secured as is wellunderstood.

In order to secure an additional motion of the carriage 8 and thereforeof the cutters 2 carried by same the screwed nut 14 through which thescrew 9 passes and which nut is carried by the framework 38 whichsupports the carriage 8 I now form to revolve under the actions of aworm 15 engaging with worm wheel teeth 16 formed upon the revolving part14 of said nut 14, and this worm 15 is mounted in bearings which willmove vertically with said nut as same is carried by its screw 9, itsvertical motion being allowed by the flexible shaft 17 which couples theworm shaft to a horizon tal shaft 18 upon the outer end of which ahandle 19 may be placed, The handle 19 is the handle usually employed inconnection with feed screw 20 which feeds the bearings or work head ofthe wheel 5, its shaft 6 and the blank 3 to the cutters 2 causing sameto advance to carry out the depth of cut desired. The shaft '18 iscoupled by change speed gearing wheels 21, 22 and 23 to the screw 20sothat. whenever the handle 19 is used for rotating the screw 20. toadvance the blank to the cutters in order to commence the next cut(after the series of cuts throughout one revolution have been eflect ed)the rotary motion of said screw 20 will have transmitted the desiredamount of motion to the shaft 18 and therefore through the connectingshafts to the worm 15 so that the nut 14* will, by its worm wheel 16,have been advanced the proportion desirec for carrying out the increaseof movement of the cutters 2 as is ,hereinbefore described.

In another type of machine (as shown by Fig. 6) the cutters 2 merelyhave reciprocatory motion transmitted to them and remain stationary sofar as regards any further motion other than following the inclinedpaths of their guiding supports while the blank 3 carried by the shaft 6is supported by the bearings 24.- for said shaft, said bearings beingarranged to descend or move in a vertical path over the guiding surfaces2% in manner well known. The rolling actions of the blank 3 over the cutters 2 are secured as is well known and in this type of machine Iarrange the extra motion to be transmitted to the sliding bearings 24 inthe same proportion or to the same degree as I add to the motion of thecutters 2 under the former conditions hereinbefore explained inconnection with the machine shown by Figs. 1 to 5 of the drawings.

When making use of ,reciprocating rack cutters for producing spurgearing with the blank revolving or rolling over said rack cutters thespace moved through the tangential path by said cutter travel has toagree with the space that the revolving blank advances during eachcutting operation, and I can carry out my method of advancing the cutterso that the depth and leading cutting edge of each cutting portion willalways act as is hereinbefore described when producing said spur teeth,the same as when producing double helical or single helical teeth.

When producing racks I follow the same method of feed for the rack tothe cutter or vice-versa that I follow according to the otherproductions hereinbefore described,

shown cutter and this I carry out by devices as is by Fig. 17 in which Iuse the rack 20 for producing the rack 20.

Such being the nature and object of my invention what I claim is 1. Thatimprovement in the method of generating gear teeth, which consists inimparting to a cutter having a depth cutting edge, a leading cuttingedge, and a following cutting edge, an entering movement advancing thecutter into a moving blank, and a lateral movement at an angle to theentering movement, said movements causing the depth and leading cuttingedges to effect substantially the entire cut.

2. That improvement in the method of generating the teeth of gearwheels, which consists in imparting to acutter having a depth cuttingedge, a leading cutting edge, and a following cutting edge, an enteringmovement advancing the cutter into a rotatingblank, and a lateralmovement at an angle to the entering movement, said movements causingthe depth and leading cutting edges to effect the major portion of thecut, and the following cutting edge to cooperate with the rotating blankin effecting a minor portion of the cut.

3. A machine for generating gear teeth, comprising means for supportingand moving a blank, a cutter having a depth cutting edge, a leadingcutting edge, and a following cutting edge, and means for imparting tothe cutter an entering movement advancing the cutter into the blank, anda lateral movement at an angle to the entering movement, said movementscausing the depth and leading cutting edges to effect the major portionof the cut.

4. A machine for generating the teeth of gear wheels, comprising meansfor supporting and rotating a blank, a cutter having a depth cuttingedge, a leading cutting edge, and a following cutting edge, and meansfor imparting to the cutter an entering movement advancing the cutterinto the blank, and a lateral movement at an angle to the enteringmovement, said movements causing the depth and leading cutting edges toefitect the major portion of the cut, and the fol lowing cutting edge tocooperate with the rotating blank in effecting a minor portion of thecut.

A machine for generating the teeth of gear wheels comprising a rotaryshaft carrying the blank to be cut, change speed gearing for rotatingsaid shaft, bearings for said shaft and gearing, means for transmittingmotion to said gearing, a cutting tool, bearings therefor, means fortransmitting reciprocatory motion to said tool, means for moving thetools tangentially over the blank, and other means for intermittentlygiving additional tangential motion to said tool.

6. A machine for generating the teeth of gear wheels comprising a shaft,adapted to hold a blank, sliding bearings on which said shaftis mounted,supports, for said bearings, cutters having depth cutting edges, leadingcutting edges and following cutting edges, cutter operating mechanismincluding means for laterally moving the cutters, means for advancingthe cutters into the blank, supplemental means for giving an additionallateral movement to the cutter, and means for sliding the said bearingsto carry the blank into the path of the cutters, the arrangement beingsuch that the depth and eading cutting edges effect the major portion ofthe cut.

ALLAN GREEN.

